Japanese Unexamined Patent Application Publication 2009-31003 (“JP '003”), below, discloses a dual pressure sensor for detecting pressures, of that which is to be measured, with each of two pressure sensors. The dual pressure sensor as set forth in JP '003 can be installed in, for example, a valve unit of a flow control valve as set forth in Japanese Unexamined Patent Application Publication 2009-115302, below. In this case, the dual pressure sensor detects both the fluid pressures on the upstream side of the valve unit and on the downstream side of the valve unit, and outputs to a flow measuring device for controlling the flow control valve. The flow measuring device calculates the flow of the fluid flowing within a flow path of the flow controlling valve based on the differential pressure between the fluid pressure on the upstream side and the fluid pressure on the downstream side.
Note that this pressure sensor has a temperature characteristic wherein the output value will fluctuate with the temperature at the time of use. In order to calculate the flow of the fluid accurately when using a pressure sensor having this type of temperature characteristic, it is necessary to perform accurate temperature correction on the output value of the pressure sensor to eliminate from the output value the fluctuation portion due to temperature variation. Because of this, in JP '003, a temperature sensor is provided in each of the two pressure sensors, and the temperature detected by the temperature sensor is used to correct the values detected by each of the pressure sensors.
Because it is necessary to provide two temperature sensors for the one dual pressure sensor in the dual pressure sensor in JP '003, described above, it has been difficult to respond to demands for reduced parts counts and costs.
Given this, the object of the present invention is to provide a dual physical quantity sensor wherein it is possible to reduce parts counts and costs.